Reconstructing a primary signal from many secondary signals

• US 5,519,735 A
• Filed: 04/28/1994
• Issued: 05/21/1996
• Est. Priority Date: 04/28/1994
• Status: Expired due to Term

• Current Assignee: Intellectual Ventures I LLC (Intellectual Ventures LLC)
• Original Assignee: Lockheed Martin Space Operations Company (Martin Marietta Corporation)
• Inventors: Wilhoyte, Michael E., Rice, Bart F.
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Bocure, Tesfaldet
• Application Number:
  US08/234,231
• Time in Patent Office: 754 Days
• Field of Search: 375/100, 375/40, 375/11, 375/12, 375/14, 375/15, 375/260, 375/261, 375/229, 375/232, 375/233, 375/230, 375/347, 375/350, 375/349, 375/316, 375/230, 375/235, 455/132, 455/136, 455/137, 455/138, 455/139
• US Class Current: 375/347
• CPC Class Codes: H04B 7/005 Control of transmission; Equalising

Abstract

An original signal, different portions of which are captured by two or more different receivers, is reconstructed from the outputs of the various receivers. In a first embodiment, signal reconstruction is achieved by first converting the analog receiver outputs into digital signals and then shifting the frequency of at least one of the digital signals such that a frequency difference is introduced between at least two of the digital signals. Thereafter, each digital signal is processed through a corresponding filter (38, 40) to derive filtered signals. These filtered signals are combined to derive a primary output signal which is a representation of the original signal. After the primary output signal is derived, it is passed on to an error determiner (44) where an error component is computed. This error component is used to adjust the parameters of the filters (38, 40) in such a manner as to reduce the error component. In an alternative method, the original signal is reconstructed by first processing all but one of the digital signals through a corresponding (114) filter to derive one or more filtered signals. The filtered signal or signals are combined with the digital signal which was not filtered to derive an intermediate output signal. The intermediate output signal is processed through another filter (120) to derive a primary output signal representative of the original signal. As with the first method, the primary output signal is sent to an error determiner (126) where an error component is computed. This error component is used to adjust the parameters of all of the filters (114, 120) to reduce the error component. The present invention provides a robust solution for reconstructing multichannel signals which is capable of tolerating variable frequency overlaps, relative time delays between signals on the multiple channels, and some degree of frequency offset.

Claims

1. A method for deriving a primary output signal from a plurality of secondary signals, comprising the steps of:

receiving a first input signal and a second input signal;

processing said second input signal through a first filter having a first set of parameters to derive a filtered signal;

combining said filtered signal with said first input signal to derive an intermediate output signal; and

processing said intermediate output signal through a second filter having a second set of parameters to derive said primary output signal;

wherein the step of processing said intermediate output signal comprises the sub-steps of;

deriving a set of parallel filtered values from said intermediate output signal, said set of parallel filtered values being orthogonal relative to each other; and

processing said set of parallel filtered values in parallel to derive said primary output signal.

2. The method of claim 1, further comprising the steps of:

determining an error component using said primary output signal; and

adjusting said first and second sets of parameters to reduce said error component.

3. The method of claim 1, wherein one of said input signals is time-delayed relative to the other input signal.

4. The method of claim 1, further comprising the step of:

prior to processing said second input signal, shifting at least one of said input signals in frequency relative to the other to introduce a selected frequency difference between said input signals.

5. A method for deriving a primary output signal from a plurality of secondary signals, comprising the steps of:

receiving a first input signal and a second input signal;

processing said second input signal through a first filter having a first set of parameters to derive a filtered signal;

combining said filtered signal with said first input signal to derive an intermediate output;

signal; and

processing said intermediate output signal through a second filter having a second set of parameters to derive said primary output signal;

wherein the step of processing said intermediate output signal comprises the sub-steps of;

processing said intermediate output signal through a lattice filter to derive a set of parallel filtered values, said set of parallel filtered values being orthogonal relative to each other; and

processing said set of parallel filtered values in parallel through an adaptive filter to derive said primary output signal.

6. The method of claim 5, further comprising the steps of:

determining an error component using said primary output signal; and

adjusting said first and second sets of parameters to reduce said error component.

7. The method of claim 5, wherein one of said input signals is time-delayed relative to the other input signal.

8. The method of claim 5, further comprising the step of:

prior to processing said second input signal, shifting at least one of said input signals in frequency relative to the other to introduce a selected frequency difference between said input signals.

9. A signal processing system, comprising:

a first filter having a first set of parameters, for processing a first input signal to provide a filtered signal;

a signal combiner for combining said filtered signal and a second input signal to derive an intermediate output signal; and

a second filter having a second set of parameters, for processing said intermediate output signal to derive a primary output signal;

wherein said second filter comprises;

a lattice filter for processing said intermediate output signal to derive a set of parallel filtered values, said set of parallel filtered values being orthogonal relative to each other; and

an adaptive filter, having said second set of parameters, for processing said parallel filtered values in parallel to derive said primary output signal.

10. The system of claim 9, wherein said first filter is a transversal filter.

11. The system of claim 9, further comprising:

an error determiner for determining an error component based on said primary output signal; and

means for adjusting said first and second sets of parameters to reduce said error component.

12. The system of claim 9, further comprising:

a first receiver for receiving a portion of an original signal, and outputting a first signal portion;

a second receiver for receiving another portion of said original signal, and outputting a second signal portion;

a first converter for converting said first signal portion into said first input signal; and

a second converter for converting said second signal portion into said second input signal.

13. A signal processing system, comprising:

a frequency shifting mechanism, said mechanism receiving first and second input signals, and shifting at least one of said input signals in frequency relative to the other input signal to introduce a selected frequency difference between said input signals, said mechanism providing first and second output signals;

a first filter, having a first set of parameters, for processing said first output signal to provide a filtered signal;

a signal combiner for combining said filtered signal and said second output signal to derive an intermediate output signal; and

a second filter, having a second set of parameters, for processing said intermediate output signal to derive a primary output signal;

wherein said second filter comprises;

a lattice filter for processing said intermediate output signal to derive a set of parallel filtered values, said set of parallel filtered values being orthogonal relative to each other; and

an adaptive filter, having said second set of parameters, for processing said parallel filtered values in parallel to derive said primary output signal.

14. The system of claim 13, wherein said first filter is a transversal filter.

15. The system of claim 13, further comprising:

an error determiner for determining an error component based on said primary output signal; and

means for adjusting said first and second sets of parameters to reduce said error component.

16. The system of claim 13, further comprising:

a first receiver for receiving a portion of an original signal, and outputting a first signal portion;

a second receiver for receiving another portion of said original signal, and outputting a second signal portion;

a first converter for converting said first signal portion into said first input signal; and

a second converter for converting said second signal portion into said second input signal.